module Main where

import System.Environment (getArgs)

main :: IO ()
main = do
  input <- readFile . head =<< getArgs
  putStrLn $ unwords ["Part 1:", show $ part1 input]
  putStrLn $ unwords ["Part 2:", show $ part2 input]

part1 :: String -> Int
part1 = length . uncurry (filter . isFresh) . parse
  where
    isFresh :: [(Int, Int)] -> Int -> Bool
    isFresh fresh ing = any (contained ing) fresh

    contained :: Int -> (Int, Int) -> Bool
    contained a (x, y) = x <= a && a <= y

parse :: String -> ([(Int, Int)], [Int])
parse = (\(ranges, ingredients) -> ((map parseRange ranges), map read (drop 1 ingredients))) . span (/= "") . lines
  where
    parseRange :: String -> (Int, Int)
    parseRange s = case span (/= '-') s of
      (start, '-' : end) -> (read start, read end)
      _ -> error $ "parseRange: expected a string on the form \"NUM-NUM\", got \"" <> s <> "\""

part2 :: String -> Int
part2 = error "Not implemented"

testInput :: String
testInput =
  unlines
    [ "3-5",
      "10-14",
      "16-20",
      "12-18",
      "",
      "1",
      "5",
      "8",
      "11",
      "17",
      "32"
    ]